Proprioception involves neuromuscular receptors in the skeletal muscles and on the surface of the tendons. These receptors provide constant feedback to the brain regarding movement, posture, changes in equilibrium, knowledge of position, weight, and resistance against its body parts. Using this feedback, the brain is typically able to correct or adapt to changes in these parameters. Amputees, and particularly amputees who have been fitted with prostheses, must learn to move their natural and prosthetic limbs without the benefit of proprioceptive feedback from the limb that is no longer present.
In cases of limb amputation, it is typically necessary for the amputee to undergo rehabilitation in order to regain functionality that is as close to normal as possible. In particular, if the amputated limb is replaced with a prosthesis, it is necessary for the amputee to learn to use the prosthesis in a way that will maximize restored functionality. The rehabilitation prescribed in such cases is designed to modify the amputee's proprioception such that he or she learns to use the prosthesis in a manner that approximates that of the lost limb.
At the same time, amputees often sense that the amputated limb is still present. This is known as Phantom Limb Syndrome. Phantom sensations can occur as passive proprioceptive sensations of the limb's presence, or more active sensations such as perceived movement, pressure, pain, itching, or temperature. The etiology of the phantom limb phenomenon is not well understood; both neurological and psychological explanations have been postulated. The sensations can be distressing, and patients are often counseled to ignore or suppress them.
Still further, after many types of major surgery, including amputation, moderate forms of exercise are prescribed as beneficial to the healing process. Exercise that directly affects the wounded area, e.g. amputation cite, while particularly helpful for increasing blood flow and reducing atrophy and stiffening, also brings associated risks of increasing damage to the wounded tissue, such as through trauma or excessive stress.
It would be advantageous to provide a device that allows an amputee to re-direct and use the sensory perceptions associated with a phantom limb in re-establishing proprioception with respect to his or her prosthesis. It would also be desirable to provide a system that allows an amputee to obtain the benefits of exercise and a desired level of vaso-stimulation without risking tissue damage.